1. Field of the Invention
The present invention relates generally to the field of personnel safety, and more specifically, the invention relates to a portable proximity-sensing system which serves to establish a safety zone for individuals engaged in activity near a potentially hazardous area. The portable proximity-sensing system alerts an individual near or within a safety zone that there has been undesirable breach of the safety zone.
2. Related Art
Following are some related art/technical paper references:
“Micropower Impulse Radar: ‘Genie on a Chip’ technology opens many new doors for U.S. industry” at URL http://www.lln1.gov/IPand C/op96/10/100-mic.html as of Nov. 28, 1998.
“Micropower Impulse Radar (MIR)” at URL http://www-lasers.lln1.gov/lasers/idp/mir/mir.html as of Nov. 11, 1998.
“Micropower Impulse Radar: MIR Technology Overview” at URL http://lasers.lln1.gov/lasers/idp/mir/overview.html as of Nov. 11, 1998.
“Micropower Impulse Radar: MIR FAQ'3” at URL http://lasers.lln1.gov/lasers/idp/mir/faqs.html as of Nov. 11, 1998.
“Micropower Impulse Radar”; Science & Technology Review January/February 1996; pp. 16–27.
“Micropower Impulse Radar: Electronic Trip Wire” at URL http://lasers.lln1.gov/lasers/idp/mir/tripwire.html as of Nov. 11, 1998.
“Micropower Impulse Radar: MIR Strip Proximity Sensor (Smart Wire)”at URL http://lasers.lln1.gov/lasers/idp/mir/smartwire.html as of Nov. 11, 1998.
In U.S. Pat. No. 5,436,613, “System for detecting human presence in hazardous locations,” inventor Ghosh, et al. relates to a system for the detection of human presence in hazardous situations near moving machinery, where radio-frequency signal of appropriate frequency and voltage is applied to electrodes creating an electric field around them. If a foreign object is introduced into the field, the characteristics of the dielectric are modified creating a change of the value of the dissipation factor. Thus, the system detects human presence by noting the increase of the dissipation factor above a threshold value.
In U.S. Pat. No. 5,760,686, “Assembly and method for detecting errant vehicles and warning work zone personnel thereof,” inventor Toman describes a system that incorporates a detector array with one or more transmitters for emitting pulsed infrared signals along the work zone perimeter and a strobe light array for announcing when a vehicle or object has crossed into the work area perimeter.
In U.S. Pat. No. 5,939,986, “Mobile machine hazardous working zone warning system,” inventor Schiffbauer, et al. describes a system, which utilizes a transmitter with directional antenna loops strung along the machine so as to create a magnetic field that surrounds the machine. The warning system further includes, as another component, a receiver carried by an individual, which alarms when the user enters the working zone of the machine.
In U.S. Pat. No. 6,288,651, “Portable roadway perimeter alarm,” inventor Souza describes a system that uses shock or impact sensors mounted into highway marker/warning cones or uses a pressure sensitive switch that is activated by running over a pneumatic hose to activate a radio beacon that warns workers of a work-zone perimeter violation.
In U.S. Pat. No. 6,340,139 B1, “A highway grade crossing vehicle violation detector,” inventor Hilleary describes an alarm monitor for a railroad grade crossing, the grade crossing having an island activation relay that is activated in response to an approaching train, the alarm monitor including a micropower impulse radar (MIR) responsive to pedestrians and motor vehicles in a prohibited area of the crossing island during activations.
In U.S. Pat. No. 6,351,234, “Combination microwave passive infrared motion detector with anti-masking evaluation,” inventor Choy describes a motion detector system with microwave and passive infrared sensors, with signal processing logic for initiating an anti-masking evaluation upon detection of certain conditions. The detector samples the sensor signals and compares the signals to a series of possible outcomes, where some of the possible outcomes represent masking conditions and others represent normal conditions. A match with masking conditions results in an alarm signal being generated.